Latch and guide assembly for a dropout electrical fuse

ABSTRACT

A fuse assembly including a pivotally mounted fuse holder having a fusible element disposed therein. The fuse assembly is of the dropout type and adapted for indoor or outdoor use in relatively high voltage circuit applications, such as 34.5 KV. The fuse holder is disposed in the fuse assembly generally vertically with the lower end of the fuse holder being supported by a hinge assembly on which the fuse holder may pivot. The upper end is latched in place by a simplified latch assembly which includes a cantilevered span and locking recess into which a complementary locking and retaining protrusion on the fuse holder may be captured upon the placing of the fuse holder in a normal electrically conductive position. The span is resilient, so as the fuse holder is brought into contact with the latch assembly the span rises vertically under the influence of the previously described protrusion or projection until the protrusion aligns with the recess at which point the recess is lowered onto the top of the fuse so that the recess captures the protrusion. In certain instances, a chargeable kickout spring is disposed on the span so that when the fuse blows the kickout spring will then force upper portions of the fuse holder outwardly away from the upper contact or latch means to a dropout position in which an insulating gap is interposed between the lower and upper contacts of the fuse assembly.

United States Patent 1 Carothers [451 Nov. 20, 1973 LATCH AND GUIDE ASSEMBLY FOR A DROPOUT ELECTRICAL FUSE Primary ExaminerBemard A. Gilheany Assistant ExaminerF. E. Bell Attorney-A. T. Stratton et al.

[57] ABSTRACT A fuse assembly including a pivotally mounted fuse holder having a fusible element disposed therein. The fuse assembly is of the dropout type and adapted for indoor or outdoor use in relatively high voltage circuit applications, such as 34.5 KV. The fuse holder is disposed in the fuse assembly generally vertically with the lower end of the fuse holder being supported by a hinge assembly on which the fuse holder may pivot. The upper end is latched in place by a simplified latch assembly which includes a cantilevered span and locking recess into which a complementary locking and retaining protrusion on the fuse holder may be captured upon the placing of the fuse holder in a normal electrically conductive position. The span is resilient, so as the fuse holder is brought into contact with the latch assembly the span rises vertically under the influence of the previously described protrusion or projection until the protrusion aligns with the recess at which point the recess is lowered onto the top of the fuse so that the recess captures the protrusion. In certain instances, a chargeable kickout spring is disposed on the span so that when the fuse blows the kickout spring will then force upper portions of the fuse holder outwardly away from the upper contact or latch me'ans to a dropout position in which an insulating gap is interposed between the lower and upper contacts of the fuse assembly.

9 Claims, 8 Drawing Figures S POINTA 64 2 7 PV it 72 73 sal fig v ll w I PATENTEDuuvzolsvs 3.774.137 SHEET 3U 3 POINTA FIG.8

LATCH AND GUIDE ASSEMBLY FOR A DROPOUT ELECTRICAL FUSE CROSS REFERENCE TO RELATED APPLICATIONS The subject matter of this application is related to the concurrently filed and copending application entitled Dropout Fuse Structure With Leaf Spring" Ser. No. 291,468 (Westinghouse Case 42,697) by H. l... Miller and W. G. Shaw filed Sept. 22, 1972.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to circuit interrupters and more particularly to dropout fuses.

2. Description of the Prior Art Prior art fuse structures are exemplified by the Frink et al. U.S. Pat. No. 3,447,114 issued May 27, 1969. This prior art structure employs a more complicated kickout action-spring latch assembly employing two separately spring-loaded and interconnected levers, one of which is for the purpose of latching the fuse in place and the other of which is for kicking the fuse out of contact when the latching lever has been forced away from the fuse by a separate element internal to the'fuse which initiates the forcing operation when the fuse blows. It would be convenient to provide a'combination latching and kickout mechanism employing at most one pivotably mounted, coil spring-loaded moving part. It would also be convenient to provide a com.- bination' latching and kickout mechanism in which a resilient leaf spring type latching mechanism is employed rather than a coil spring-lever type latching mechanism.

SUMMARY OF THE INVENTION In accordance with the invention, an electrical fuse assembly having a base and a generally vertically spaced contact portion has disposedthereon a generally cylindrical fuse body having end ferrules and 'interposed and interconnected fusible material with the fusible material being surrounded by a protective structure or fuse housing. The lower contact member, in addition, comprises a hinge upon which one ferrule of the fuse body may be pivotally mounted by way ofa circu- Iar protrusion. The upper contact assembly has therein 1 a latching member which in one embodiment includes a generally cantilevered, resilient, electrically conducting member having a small opening thereon. Whenthe fuse structure is pivoted into contacting position with the previously mentioned upper contact assembly, a portion of the moving fuse causes the resilient cantilevcred structure to pivot upwardly as the fuse holder is moved until a protrusion on the fuseholder aligns itself means may bepivotably disposed on the underside of the cantilevered latching mechanism and pivot relative thereto, so that when thefuse is brought into contact with the cantilevered resilient latching means, it causes the auxiliary or second spring-loaded kickout element to be charged or moved backward relative to the motion of the fuse. When the fuse is then in its latched position, the kickout mechanism is fully charged. When the fuse blows, a push rod or plunger internal to the fuse is actuated to move vertically out of the end ferrule of the fuseto force itself against or engage the cantilevered mechanism causing the cantilever to move upwardly so that the recess is moved out of a retaining position with respect to the previously described fixed protrusion on the end ferrule. When this happens, the charged kickout mechanism forces the fuse to pivot outwardly away from the combination kickout latch means.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be had to the preferred embodiments, exemplary of the invention, as shown in the accompanying drawings, in which:

FIG. I is a side view in elevation of a fuse assembly inthe closed position and which shows the latch assembly of the present invention;

FIG. 2 is a front elevation of the fuse assembly shown in FIG. 1;

FIG. 3 is a front elevation of another embodiment of the invention in which two parallel fuses are placed in a common fuse assembly;

FIG. 4 shows a partially cutaway view of the latch as sembly embodying the teachings of the present invention;

FIG. 5 is a top cutaway view of the latch assembly shown in FIG. 4;

FIG. 6 is another embodiment of a latch assembly which embodies the teachings of the present invention;

FIG. 7 is a view similar to FIG. 6 to show one position during the closing or opening operation of the fuse assembly as shown in the previous figures; and

FIG. 8 is a view similar to FIG. 7 but showing another position in the closing or opening operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and FIG. 1 in particular, a fuse assembly 10 embodying the teachings of the present invention is shown. Fuse assembly 10 includes a support-base 11 upon which are fastened and preferably spaced in a vertical orientation two insulating support members 12 and 14. Upper insulating support member 12 is spaced vertically above lower insulating support member 14. Support members 12 and 14 may be porcelain insulating support members but are not limited to such material. Adjacent upper insulating support member 12 is the kickout latch assembly or bracket means 16 having a protective cover 18 in this embodiment. Fastened to or adjacent the lower insulating support member 14 is the hinge assembly or bracket means 20 having an electrically conducting frame or support piece 22. lnterposed between upper bracket means or kickout latch assembly 16 and lower hinge assembly or bracket means 20 is a fuse unit or fuse means 24 comprising a fuse holder 25 inside of which is disposed a fusible element 25F and adjacent the ends of which are disposed an upper end ferrule or terminal 26 and a lower end ferrule or terminal 28. Lower end terminal 28 has as part thereof a support trunnion 38 which is pivotably disposed in a corresponding opening or groove in frame 22. Lower end ferrule or terminal 28 has also disposed thereon an arcuate or sector shaped portion 40 which is useful in controlling or guiding the movement of the fuse unit during an opening or closing operation and a cylindrical projecting portion 42 disposed near the back portion of lower end ferrule 28 which is useful in positioning the fuse upon closing. Adjacent cylindrical projecting portion 42 is a hinge lifting eye or lower end ferrule force transmitting member 44 which is useful in lifting the fuse out of frame 22 and in providing a means against which force may be applied by a leaf spring or spring member 46. Disposed adjacent to frame or support piece 22 is a terminal means or assembly 47 which electrically. connects with or is in electrical contact with the lower end ferrule 28 of fuse unit 24 so that fuse 24 may be used to control an external electrical circuit which may be connected to terminal 47. An electrically conducting path may exist-between end ferrule 28 and terminal 47 through frame 22 or through the hinge lifting eye 44 and leaf spring 46 to portions of the frame 22 and thence to terminal 47. It is to be understood that frame 22 need not be electrically conducting if the hinge lifting eye 44 and leaf spring 46 are electrically conducting and, alternately, hinge lifting eye 44 and leaf spring 46 need not be electrically conducting if frame 22 is electrically conducting. It is also to be understood that frame 22 and hinge lifting eye 44 and leaf spring 46 may all be electrically conducting. The kickout latch assembly or bracket means 16 has disposed therein a kickout and latching mechanism 27, the structure and use of which will be described hereinafter. An eye hook 36 is shown adjacent a portion of upper end ferrule 26 on fuse 24. Eye hook 36 may be employed for pivoting fuse unit 24 into or out of electrical contact with the kickout latch assembly mechanism 27.

Referring now to FIG. 2, a front elevation of the fuse structure shown in FIG. I is depicted. Base 11 and upper and lower insulating support members 12 and 14 (not shown in this figure) combine to form a combination support member for fuse unit 24. It can be seen from this view that housing or weather protecting cover 18 for kickout latch assembly 16 flares outwardly and upwardly from the region of base 11 to avoid contacting end ferrule 26 of fuse holder 25 while it moves into the latching and kickout mechanism 27.

It can also be seen that lower hinge assembly or bracket means 20 has a portion of its frame 22 bent or flared outwardly to provide easy access to the portions of the lower end ferrule 28 when placing it in hinge assembly 20. Trunnion 38 is shown disposed between the two outwardly projecting parts of the frame 22. The arcuate sections 40 and cylindrically projecting members 42 are shown in their respective positions for a fuse in the normally closed position.

Referring now to FIG. 3, another embodiment of the invention in which two fuse units 24R and 24L form part of a fuse assembly 10'. Such a fuse assembly is desirable in high power electrical circuit conditions where a large amount of current, necessitating parallel fuse paths, is required. Fuse assembly 10' includes a common base 11 which is similar to base 11 shown in FIG. 2. Disposed on base 11 are vertically spaced upper and lower insulator support members 12' and 14', respectively. The left fuse unit or means 24L comprises a fuse holder 25L having upper and lower end ferrules similar to those described with respect to FIGS. 1 and 2. The lower ferrule of fuse holder 25L is adapted to be pivotally supported by hinge assembly or bracket means 20L. The upper ferrule is adapted to be swung, pivoted or moved into electrical contact with the combination kickout and latch bracket assembly 16L. There is a terminal 47L for connection to a conductor of an external electrical circuit to be controlled by fuse assembly 24L. Fuse assembly 24R on the right has a corresponding fuse holder 25R, the lower ferrule of which is pivotally disposed in lower hinge assembly 20R and the upper end ferrule of which is adapted to be pivotally swung into connection with upper hinge assembly 16R. Fuse holder 24R also has a lower terminal 47R for connection with an external electrical circuit to be protected by fuse 24R. In some instances, fuse units 24L and 24R may be connected to the same electrical circuit to provide parallel fusing for that circuit. I

Referring now to FIG. 4, an upper kickout and latch assembly or bracket means 16 such as shown in FIGS. 1 and 2 and similar to the kickout latch assembly 16L and 16R shown in FIG. 3 is illustrated. The combination kickout latch assembly 16 is disposed upon a vertically oriented base means 50 having holes 52 therein for specific mounting purposes. In one embodiment, a

bolt or fastening means 53 supports fuse kickout and latch assembly 16 on base 50. Base 50 may be fastened or attached to the previously described porcelain insulator support means 12 (not shown). in addition, base 50.may be electrically conducting so that an external electrical circuit may be connected through it to the kickout latch assembly 16. Kickout latch assembly 16 comprises a cover 18 which covers the top and side portions of the kickout latch assembly mechanism 27 and which is adapted to fit around the previously described base member 50 so that bolt 53 may be threaded through it or attached to it for support purposes. The kickout and latch assembly mechanism 23 comprises three portions: an upper portion 54, a lower portion 56 and an intermediate or upper and lower adjoining piece or bracket support piece 58. The upper portion 54 of the kickout and latch mechanism comprises a cantilevered ring or span 60 rigidly supported at its left end in the vicinity of bolt 53 and generally free to vibrate, move or oscillated vertically at its right end. Cantilevered portion 60 comprises resilient electrically conducting support material such as, but not.

limited to, brass, steel, copper or alloys thereof. To the right of cantilevered section 60, as viewed in FIG. 4, is the top piece or latch portion 62 for the upper kickout and latch mechanism 54. Top piece 62 has in the left portion thereof, as viewed in FIG. 4, an opening 73, the purpose of which will be described later. The right portion of top piece 62 has an upper guide means 64 which extends angularly upward from the plane of top piece 62 and top piece 62 also has side guide means 66 which extend angularly outwardly from the vertical portions of top piece 62. By referring to FIG. 5, the angular displacement of the side pieces 66 may be easily seen. The upper portion of the kickout and latch assembly 54 is joined to the lower portion 56 by an intermediate bracket means support piece or joining member 58 which abuts the previously described base 50. Joiningpiece 58 as illustrated is integral with cantilevered portion 60 of the upper portion 54 and with the grasping members 68 of the lower portion of the kickout-latch assembly 56. By referring once again to FIG. 5, the top view of the ferrule grasping members 68 show them to be generally horizontal members which radiate or extend outwardly from joining piece 58 at a predetermined angle with respect to a line perpendicular to joining piece 58. Grasping members 68 double or loop back upon themselves on both the right and left sides to form U-shaped members 68U. The members 68U provide a grasping force for the ferrule of a fuse element such as ferrule 26 as shown in FIG. 1. They also provide the main path of electrical conductivity between the ferrule 26 as shown in FIG. 1 and the electrically conducting end portion 50 so that an external electrical circuit may be connected through the latch assembly 16 to the ferrule 26 which electrical circuit may be completed through the fuse element 25F as shown in FIG. 1 and the lower hinge assembly and finally the terminal 47 also shown in FIG. 1. It is envisioned in the embodiment of the invention shown in FIGS. 4 and 5 that although the upper portion 54 of the kickout and latch assembly mechanism 27 may be electrically conducting, it is primarily constructed with a view toward latching the fuse and kicking it out upon the blowing of the fuse element such as F as shown in FIG. 1.

Referring once again to FIG. 4, in one embodiment of the invention, a pivotally mounted spring-loaded kickout lever 70 may be suspended from the lower side of upper kickout and latch assembly mechanism 54 intermediate the cantilevered portion 60 and the top piece 62 just to the left of the opening or hole 73 previously described. The kickout lever 70 includes a structural support member 71 having an opening at the top through which the previously described pivot pin or rod 72 may feed or pass so that structural member 71 may pivot about the rod 72 with respect to the upper portion of the kickout and latch mechanism 54. At the other end of the structural support member 71 is another recess or recesses through which the pin or rod 74 may be assembled. Pin or rod 74 has disposed thereon a wheel or roller 76 for rolling movement against the end ferrule of the fuse such as fuse unit 26 shown in FIG. 1.

By referring to FIGS. 4 and 5 concurrently, it can be seen that an uncharged kickout lever 70 is disposed in a downward angular position to the right with respect to a vertical line through the upper rod or pin 72 as shown in FIG. 4. Kickout lever 70 is maintained in its angular position by a biasing spring or chargeable spring member 71, one end of which is coiled around the previously described upper pivot pin or rod 72 and biased against the cantilevered portion 60 of the upper portion of the kickout and latch assembly 54. The other end of the chargeable spring member 78 is disposed against a lip 82 which cooperates with the vertical portions of the support structure 71 to form a groove 80. Spring 78 therefore may be considered to cooperate with the structural member 71 to bias the kickout lever 70 into the angular position shown in FIGS. 4 and 5. The kickout latch assembly 16 shown in FIGS. 4 and 5 is especially adapted for an outdoor dropout type fuse assembly, that is, a fuse assembly meant to be applied outdoors in an electrical substation where weather, especially ice producing weather, may affect the operation of the fuse. This fuse is also meant to dropout or kickout once a fuse element such as 25F shown in FIG. 1 has blown or fused. The kickout member 70 is adapted to provide an outward counterclockwise force to dropout fuse when the fuse element has blown so that the fuse may pivot clockwise outwardly away from kickout and latch assembly 16. The cover 18 provides protection from the weather from the top and sides but not from the front or the bottom. In some instances, ice may accumulate between the fuse ferrule such as 26 shown in FIG. 1 and portions of the kickout and latch assembly 16 such as shown in FIGS. 4 and 5. More specifically, a vertical protrusion on the upper end ferrule of the fuse not shown may be frozen into the hole or opening 73 such as shown in FIG. 4. In this situation, the spring force of the spring 78 in the kickout lever provides the force to help break the ice in such a circumstance.

Referring now to FIG. 6, an indoor non-dropout type fuse employing similar component parts as the outdoor dropout type fuse shown in FIGS. 4 and 5, is shown;

The primary difference between the indoor nondropout type fuse mechanisms 27', such as shown in FIG. 6, and the outdoor dropout type fuse mechanism 27, such as shown in FIGS. 4 and 5, is the omission of the kickout lever 70. In addition, kickout and latch assembly 16 for the outdoor dropout type fuse includes a weather protective cover 18 whereas latch assembly 16 shown in FIG. 6 does not require or include a protective cover. It will be noted that latch assembly 16' shown in FIG. 6 includes an electrically conductive piece 50' having holes 52' therein, one of which is adapted to have a bolt 53 disposed therein which secures the latch mechanism 27' to the electrically conducting support member 50. Latch mechanism 27' has three identifiable portions, namely a top or upper portion 54, a lower portion 56' and an intermediate or joining portion 58, all of which may be integral and constructed from the same piece of electrically conductive material which may bebent into the various required shapes. Lower portion 56 includes the previously described grasping members 68' which are similar to members 68 shown in FIGS. 4' and 5. Upper member 54 includes a cantilevered portion 60', a rectangular hole 73', a top piece 62', a corresponding angularly oriented upper guide means 64' and left and right guide means 61 shown as part of the top piece 62, the hole or recess 73' being intermediate to the upper top piece 62 and the cantilevered section 60'.

OPERATION OF THE KICKOUT LATCH ASSEMBLY Referring to FIGS. 7 and 8, the operation of the combination latching and kickout mechanism is shown. In FIG. 7, a fuse unit 24 is shown being closed by being pivoted in direction into the upper portion 54 0f the kickout and latching assembly mechanism 27, the bottom portion 56 not being shown for convenience of illustration. It can be seen that cantilevered member 70 which is attached to the intermediate section 58 which, in turn, is attached to the support member 50 by bolt fastening means 53 has a pivot point designated point A in FIG. 7. The cantilever 60 and the rest of the mechanism to the right thereof and attached thereto pivots, oscillates or rotates upwardly and downwardly about this point. As the ferrule 26 moves into the opening created by the control guide members 66 and 67, the axially projecting portion 94 makes contact with the lower part of top piece 62 whereupon the upper part of the virtually axially projecting portion 94 tracks virtually horizontally along the lower portion of top piece 62 for the period of time it takes the axially projecting portion 94 to reach the hole 73. This causes the cantilevered portion 60 of the top portion 54 to move upwardly in the direction 67. It will move upwardly and stay in an upward position until portion 94 is under hole 73. While this is happening, ferrule 26 contacts the wheel 76 of the spring-loaded lever or kickout means 70 causing lever 70 to rotate in the direction of rotation 84 about pivot pin or rod 72 to charge the spring 78. This operation will continue until the actually projecting portion 94 is engaged or captured by outer perimeter of hole 73 as described previously.

Referring now to FIG. 8, that portion of the latch and kickout assembly and fuse shown in FIG. 7 is also shown in FIG. 8 but with the fuse advanced further in the direction 90 to the stop point or to the position where the fuse is secured for protection purposes in the circuit in which it is connected. It will be noted that upper portion 54 has been rotated upwardly in direction 67 and is now seated against the top nut 90 on the fuse assembly 24. It can be seen that the hole or recess 73 between the cantilevered section 60 and the top piece 62 has come into engagement with the axially projecting portion 94 with the fuse unit 24 being rigidly held in position by the force of the spring 78 on the lever 70 pushing against the frame 71 to cause the roller 76 to push end ferrule 26 as far to the right as possible so that projecting portion 94 is abutted forcefully up against the right side of hole 73 as shown in FIG. 8. The position of the ferrule 26 causes charging of the spring 78, as previously described, so that lever 70 is maintained in a high potential energy mechanically charged position. When a fuse element, such as 25F as shown in FIG. 1, blows an axially movable member or plunger 92 inside of fuse body 25 is caused to move upwardly through nut 90 against the bottom surface of top piece 62 of the upper portion 54 of the combination kickout and latch assembly 27 so that the axially projecting member 94 is cleared from the peripheral portions of hole 73. When this occurs, the force of release of the charged spring 78 causes the frame 71 of the lever member 70 to be rotated in a direction 84A about axle 72, thus thrusting or actuating the ferrule 26 in a direction to the right and freeing the upper end ferrule 26 from the upper latch and kickout assembly 27 to allow the force of gravity to cause fuse element 24 to swing downwardly and to the right in an arcuate path. It will be noted that the locking or retaining of the fuse in the vertical position and the charging of the kickout spring is accomplished with only two moving parts, one of which is spring-loaded with a coil spring, the other of which is cantilevered about a fixed support piece 50. A fuse assembly of this type is useful for fuses in a 34.5 K volt electrical system and 800 Ampere electrical system.

It is to be understood that the dropout fuse structure may be disposed in other orientations. It should also be understood that the relative placement of the hinge assembly and the latch assembly may be reversed in some circumstances. It should also be understood that the fuse assembly may be conveniently oriented at a predetermined angle between the horizontal and vertical. It should also be understood that the hinge assembly need not necessarily be the hinge assembly described in copending application Ser. No. 291,468 (W.E. Case 42,697), but may be any convenient hinge assembly, although in a preferred embodiment a hinge assembly described in copending application Ser. No. 291,468 (W.E. Case 42,697) is conveniently used with the teachings of the present invention.

The apparatus embodying the teachings of this invention has many advantages, one of which is that the latch and kickout portions of the upper latch and kickout assembly or mechanism need not be the electrically current carrying elements for the upper connector. Consequently, they may be specifically designed for structural and mechanical purposes, rather than for electrically conducting properties. Another advantage lies in the fact that the degree of movement in the latch and kickout assembly and the number of moving parts is reduced from that of the prior art by requiring only one pivot pin and apivot axis with a coil spring and cantilevered or leaf spring assembly rather than two cooperating coil spring levering mechanisms. Another advantage lies in the fact that the use of the simplified spring kickout and latching assembly requires less structural material for its construction. Another advantage lies in the fact that the latch and guide assembly or kickout and latch assembly may be used for both indoor and outdoor fuse structures merely by removing or replacing certain component parts and without changing the basic operation of the structure.

I claim as my invention:

1. A dropout fuse assembly, comprising:

a support member,

a fuse means including:

a fusible element,

a fuse holder in which said fusible element is disposed,

a first electrically conducting ferrule disposed on a first portion of said fuse holder and electrically connected to a first portion of said fusible element,

a second electrically conductive ferrule disposed on another portion of said fuse holder, spaced from said first portion of said fuse holder, and electrically connected to a second portion of said fusible element spaced from said first portion of said fusible element;

a first bracket means disposed on said support member and adapted to engage said first ferrule of said fuse means when said fuse means is disposed in said dropout fuse assembly for protecting an external electrical circuit, said first bracket means includan electrically conducting member disposed in said first bracket to electrically interconnect a portion of said external electrical circuit and said first ferrule when said fuse is disposed in said fuse assembly to protect said external circuit,

a first bracket means support piece attached to said fuse dropout assembly support member and adapted to support other members of said first bracket means,

a resilient unitary latch-guide means including:

a first portion to guide remaining portions of said unitary latch guide means into a mechanically charged condition when said first electrically conducting ferrule is brought into engagement with said first bracket means,

a second portion generally rigidly attached to said first bracket means support piece and adapted to support the remaining portions of said resilient,

unitary latch-guide means and to flex upon engagement of said first ferrule with said first bracket means to substantially contribute to said charging of said unitary latch-guide means,

a third portion integrally formed with said first and second portions and disposed intermediate said first and second portions, to latch said unitary latch-guide means in said charged condition upon said first ferrule after engagement of said unitary latch-guide means and said first ferrule,

a chargeable spring means disposed to be mechanically charged upon engagement of said first ferrule with said unitary latch-guide means by moving about a pivot point on a portion of said latch guide means to a charged position from which said spring member may move against said first ferrule of said fuse means during an opening operation of said dropout fuse assembly to assist inactuating said fuse means during said opening operation; and

a second bracket means disposed on said support member and spaced from said first bracket means and adapted to engage said second ferrule of said fuse means including an electrically conducting member disposed in said second bracket to electrically interconnect another portion of said external electrical circuit and said second ferrule.

2. The combination as claimed in claim 1 wherein said second portion of said resilient unitary latch guide means comprises a cantilevered span. I

3. The combination as claimed in claim 1 wherein said chargeable spring means includes a coil spring.

4. The combination as claimed in claim 1, comprising:

a second-ferrule force transmitting member; and

a second spring member disposed adjacent a portion of said second bracket, said second spring member being charged by said second ferrule force transmitting member and being in engagement therewith while said fuse means is disposed in said fuse assembly to protect said external circuit, said spring member being capable thereafter of discharging against said second ferrule force transmitting member to move said second ferrule movable support means a relatively smaller distance than said first ferrule is caused to move thereby to disengage said fuse means first ferrule from said first bracket.

5. The combination as claimed in claim 4 wherein 5 said second portion of said resilient unitary latch guide means comprises a cantilevered span.

6. The combination as claimed in claim 4 wherein said chargeable spring means includes a coil spring.

7. A resilient unitary latch-guide means for a fuse l0 dropout assembly, comprising:

a first portion adapted to guide remaining portions of said unitary latch-guide means into a mechanically charged position when a portion of a fuse means is brought into engagement with said latch-guide means;

a second portion generally rigidly attached to a support piece on said dropout assembly to support the remaining portions of said resilient, unitary latchguide means and to flex upon engagement of said fuse means with said latch-guide means to substantially contribute to said charging of said unitary latch-guide means;

a third portion integrally formed with said first and second portions and disposed intermediate said first and second portions to latch said unitary latchguide means into said charged position upon said fuse means after engagement of said unitary latchguide means and said fuse means; and chargeable spring means adapted to be mechanically charged upon engagement of said fuse means with said unitary latch-guide means by moving about a pivot point on a portion of said latch guide means to a charged position from which said spring member may move against said ferrule of said fuse means during an opening operation to assist in said opening operation.

8. The combination as claimed in claim 7 wherein said second portion comprises a cantilevered span.

9. The combination as claimed in claim 7 wherein said chargeable spring means includes a coil spring. 

1. A dropout fuse assembly, comprising: a support member, a fuse means including: a fusible element, a fuse holder in which said fusible element is disposed, a first electrically conducting ferrule disposed on a first portion of said fuse holder and electrically connected to a first portion of said fusible element, a second electrically conductive ferrule disposed on another portion of said fuse holder, spaced from said first portion of said fuse holder, and electrically connected to a second portion of said fuSible element spaced from said first portion of said fusible element; a first bracket means disposed on said support member and adapted to engage said first ferrule of said fuse means when said fuse means is disposed in said dropout fuse assembly for protecting an external electrical circuit, said first bracket means including; an electrically conducting member disposed in said first bracket to electrically interconnect a portion of said external electrical circuit and said first ferrule when said fuse is disposed in said fuse assembly to protect said external circuit, a first bracket means support piece attached to said fuse dropout assembly support member and adapted to support other members of said first bracket means, a resilient unitary latch-guide means including: a first portion to guide remaining portions of said unitary latch guide means into a mechanically charged condition when said first electrically conducting ferrule is brought into engagement with said first bracket means, a second portion generally rigidly attached to said first bracket means support piece and adapted to support the remaining portions of said resilient, unitary latch-guide means and to flex upon engagement of said first ferrule with said first bracket means to substantially contribute to said charging of said unitary latch-guide means, a third portion integrally formed with said first and second portions and disposed intermediate said first and second portions, to latch said unitary latch-guide means in said charged condition upon said first ferrule after engagement of said unitary latch-guide means and said first ferrule, a chargeable spring means disposed to be mechanically charged upon engagement of said first ferrule with said unitary latchguide means by moving about a pivot point on a portion of said latch guide means to a charged position from which said spring member may move against said first ferrule of said fuse means during an opening operation of said dropout fuse assembly to assist in actuating said fuse means during said opening operation; and a second bracket means disposed on said support member and spaced from said first bracket means and adapted to engage said second ferrule of said fuse means including an electrically conducting member disposed in said second bracket to electrically interconnect another portion of said external electrical circuit and said second ferrule.
 2. The combination as claimed in claim 1 wherein said second portion of said resilient unitary latch guide means comprises a cantilevered span.
 3. The combination as claimed in claim 1 wherein said chargeable spring means includes a coil spring.
 4. The combination as claimed in claim 1, comprising: a second-ferrule force transmitting member; and a second spring member disposed adjacent a portion of said second bracket, said second spring member being charged by said second ferrule force transmitting member and being in engagement therewith while said fuse means is disposed in said fuse assembly to protect said external circuit, said spring member being capable thereafter of discharging against said second ferrule force transmitting member to move said second ferrule movable support means a relatively smaller distance than said first ferrule is caused to move thereby to disengage said fuse means first ferrule from said first bracket.
 5. The combination as claimed in claim 4 wherein said second portion of said resilient unitary latch guide means comprises a cantilevered span.
 6. The combination as claimed in claim 4 wherein said chargeable spring means includes a coil spring.
 7. A resilient unitary latch-guide means for a fuse dropout assembly, comprising: a first portion adapted to guide remaining portions of said unitary latch-guide means into a mechanically charged position when a portion of a fuse means is brought into engagement with said latch-guide means; a second portion generally rigidly attached to a support piece on said dropout assembly to support the remaining portions of said resilient, unitary latch-guide means and to flex upon engagement of said fuse means with said latch-guide means to substantially contribute to said charging of said unitary latch-guide means; a third portion integrally formed with said first and second portions and disposed intermediate said first and second portions to latch said unitary latch-guide means into said charged position upon said fuse means after engagement of said unitary latch-guide means and said fuse means; and a chargeable spring means adapted to be mechanically charged upon engagement of said fuse means with said unitary latch-guide means by moving about a pivot point on a portion of said latch guide means to a charged position from which said spring member may move against said ferrule of said fuse means during an opening operation to assist in said opening operation.
 8. The combination as claimed in claim 7 wherein said second portion comprises a cantilevered span.
 9. The combination as claimed in claim 7 wherein said chargeable spring means includes a coil spring. 